Valve-gear of internal-combustion engines



UNITED STATES PATENT OFFICE.

JAMES MCKECHNIE, OF IBAEROW-IN-FUBNESS, ENGLAND, ASSIGNOR TO VICKERS LIMITED, OF LONDON, ENGLAND.

VALVE-GEAR 0F INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Patented Sept. 14., 1920.

Application filed February 27, 1920. Serial No. 361,806.

To all whom it may concern:

lle it known that 1, JAMES MoKEoHNrE, a subject of the King of Great Britain, residing at Naval Construction \Vorks, Barrowin-Furness, in the county of Lancaster, England, have invented certain new and useful improvements in or Relating to the Valve- (Jrear of Internal-Combustion Engines, of which the following is a specification.

This invention relates to the valve gear of internal combustion engines of the kind in which the exhaust and induction or inlet valves are operated by cams through cam levers which can be placed into and out of action, separate cams being employed for ahead running and astern running, which cams are brought into and out of operation by axial displacement.

According to the present invention the means for axially displacing the cams comprises a pivoted slotted lever having a slot and pin connection to a servo motor or hand actuating mechanism and so interconnected with the mounting of the cam levers that,

on reversing the engine, the levers are first moved clear of the cams, the cams are then moved. by the aforesaid slotted lever axially into their new position and the levers are finally brought into their operative positions in Contact with the reverse cams, the lever slot being shaped to provide for such succession of operations. The cam shaft itself may be axially dsplaceable with the cams and may carry two pairs of cams, one pair for each of the cani levers, and a crank or like connection to the cam levers may be employed to raise and lower them from and on to their cams, respectively before and after the movement of the pivoted lever.

In order that the said invention may be more clearly understood and readily carried into effect the same will noW be described more fully with reference to the accompanying drawings, in which Figure l is an elevation of apparatus embodying this invention, and

Fig. 2 is an elevation of the same apparatus at right angles to Fig. l, With a portion shown in section.

A is the sliding cam shaft on which are mounted the ahead and astern cams B, B', tivo pairs of such cams being shown, one pair for the inlet valve and the other pair for the exhaust valve. C, C' are the cani levers carrying rollers c which bear upon the cams B, B', the levers being mounted on the eccentrics d on the fulcrum shaft D. E, E are the valve levers for the inlet and exhaust valves F, F', the valve levers being connected by the rods e to one arm of the cam levers C, C. G is the pivoted lever operating the cam shaft A through the fork g and collar a, the lever G having the slot g at its lower end, the slot having tWo portions radial to the pivot g2 with a sloping conneet-ing portion. H is a rack on the end of a shaft i, actuated by the servo motor Jl provided with the buffer oil cylinder or dashpot K, the servo motor having a reversing valve j controlled by the reversing handle j', air under pressure being admitted through the inlet pipe j3 and passed to either end of the cylinder J, as required, through the pipes ji For convenience, the valve j 1s mounted on the oil cylinder K, which is provided With a by-pass valve to regulate the dashpot action.

The rack H gears With a pinion Z on the shaft L which is provided at its end with a crank l connected by the rod Z2 to a lever d on the fulcrum shaft D. The pinion shaft L can also be operated by the reversing hand Wheel M through the shaft m, clutch m and bevel gearing m2, the hand Wheel being brought into action by means of the clutch When required, the servo motor, however, being usually employed.

The rack H is mounted on the face of a slide h which slides upon the block [1.2 mounted on the engine casing N and carries the roller or pin h3 extending through the slot g of the lever G, the pin connecting the front and back parts of the slide between which the end of the lever extends. The mounting of the pin at both ends prevents any risk of bending the pin on operating the lever. The pivot g2 of the lever G is carried in the brackets g3 mounted on a part of the casing N. The cylinders J and K are carried by the brackets 7'2 and mounted on the face of the casing, the cylinder J being supplied with air under pressure through the reversing valve The reversing operation is carried out as followsv With the parts in the position shown The reversing handle y" is turned to allow the air to pass through the valve j into the servo motor cylinder J so as to lift the rack shaft L With the slide h and rack H. The initial movement of the rack acting trough the pinion l turns the shaft L and the crank l so as to rotate the fulcruin shaftV D and lift the rollers of the cam levers C, C from the cams B, B. During the first part of this operation the pivoted lever H is not operated as the roller h of the slide It moves through the lower radial ortion of the slot g. As soon as the mid e portion of the slot is reached the lever G turns and causes the cam shaft A to slide and to bring the astern cams. B under the rollers c. The final portion of the movement leaves the pivoted reversing lever G unaifected,vthe roller ha moving in the second radial portion of the slot g but the continued movement of the fulcrum shaft D brings the eccentrics d again into the position in which the rollers c are brought down upon the cams so that the second pair of cams B are now operative for the reversing of the envine. D On reversing the o eration of the servo motor so as to lower t e rack and slide the reverse operation on the cam levers takes lace, the eccentrics first raising the levers rom the cams B', the cam shaft being then shifted back into the position shown in Fig. 1 and the continued movement bringing the cam levers again into operation on the cams B.

In case the servo motor is out of order, the hand reversing mechanism can be brought into operation by closing the clutch m and turning the hand wheel M, whereupon the pinion shaft L effects the movement of the fulcrum shaft D and at thev same time through the pinion and rack moves the slide h to operate the reversing lever G. Instead, however, of employing a mechanical hand gear, an oil pump can be used operating the gear through the oil buffer cylinder K, using the latter as a motive power cylinder, in which case the bgpass valve in the buffer cylinder would e closed and one in the air cylinder J would be o ned.

at I claim and desire to secure by Letters Patent of the United States is 1. In reversing valve gear for internal combustion engines, axially displaceable forward and reverse cams, a valve lever adapted to coperate with the said cams, a pivoted slotted lever for effecting the axial displacement of the cams, means en aging in the lever slot for turning the sai lever through an angle for reversing urposes and means associated with the said slotted lever for raising the valve lever clear of the cams during their sliding movement.

2. In reversin valve gear for internal combustion engines, axially dis laceable forward and reverse cams, a valve lever adapted to coperate with the said cams, a pivoted cam displacing lever provided with a slot comprising two radial portions and an inclined connecting portion, a sliding' lever operating member engaging in the said slot and means associate4 with the said slotted lever for raising the valve lever clear of the cams during enga ement of the said operating member with t e inclined portion o the said slot.

3. In reversin valve gear for internal combustion engines, axially displaceable forward and reverse cams, a valve lever adapted to cooperate with the said cams, a

ivoted slotted lever for effecting the axial isplacement of the cams, means en aging in the lever slot for turning the sai lever through an angle for reversing purposes, a shaft gearing with the said lever turning means, a crank arm on the said shaft and a connection from the arm to the valve lever whereby thelatter is raised from the cams during their sliding movement.

4. In reversin valve gear for internal combustion engines, axially displaceable forward and reverse cams, a valve lever adapted to coperate with the said cams, a pivoted slotted lever for effecting the axial displacement of the cams, means en aging in the lever slot for turning the sai lever through an angle for reversing purposes, a servo motor actuating the lever turning means and means also actuated b the said servo motor for raising the valve ever clear of the cams during their turnin movement.

5. In reversing valve gear or internal combustion engines, axially displaceable forward and reverse cams, a valve lever adapted to co erate with the said cams, a ivoted slotte lever for eiiecting the axia displacement of the cams, means enga ing in the lever slot for turning the sai lever through an angle for reversing purposes, a servo motor adapted to operate the said turning means, hand o erated mechanism ada ted to be connecte up at will to the sai turning means and means operable by the servo motor and the said hand operated mechanism whereby the valve lever is raised clear of the cams during their sliding movement.

6. In reversin valve gear for internal combustion engines, axially dis laceable forward and reverse cams, a va ve lever adapted to coperate with the said cams, a pivoted slotted lever for eli'ecting the axial displacement of the cams, a slidin rack engaging in the lever slot, a reversing servo motor adapted to actuate the slidin rack, a shaft having a pinion gearing with the rack and a crank connection from the said shaft to the valve lever, for the purpose specified.

7. In reversin valve gear for internal combustion engines, axially dis laceable forward and reverse cams, a valjve lever adapted to coperate with the said cams, means for raising the valve lever clear of the cams, a pivoted lever effecting the axial is again brought into operative position on displacement of the cams and a connection the completion of the axial displacement of between the said pivoted lever and the valve the cams. 10 lever raising mechanism, whereby the said In testimony whereof, I aix my signa- 5 pivoted lever is operated for reversing purture.

poses after the valve lever has been raised clear of the cams and the said valve lever JAMES MCKECHNIE. 

